▎ 摘　　要

NOVELTY - Graphene dispersing agent i.e. 2,2'-disulfanediylbis(methylene)bis(5,8,11-tri-sec-butyl-4,7,10,13-tetraoxo-3,6,9,12-tetraazatetradecan-1-oic acid) (I) is new. USE - Used as graphene dispersing agent i.e. 2,2'-disulfanediylbis(methylene)bis(5,8,11-tri-sec-butyl-4,7,10,13-tetraoxo-3,6,9,12-tetraazatetradecan-1-oic acid). ADVANTAGE - (I): has high biocompatibility; facilitate the development of grapheme dispersion in the biomedical field; and changes its electric charge with pH value, and thus it produces pH-responsive graphene dispersion. DETAILED DESCRIPTION - Graphene dispersing agent i.e. 2,2'-disulfanediylbis(methylene)bis(5,8,11-tri-sec-butyl-4,7,10,13-tetraoxo-3,6,9,12-tetraazatetradecan-1-oic acid) of formula (I) is new. INDEPENDENT CLAIMS are also included for: (1) preparation of (I); and (2) preparation of graphene dispersion, comprising adding 5 pts. wt. (I) and 25 pts. wt. graphite powder into 10 pts. wt. water, adjusting pH to 6-7, mixing uniformly, placing the reaction mixture in ultrasound machine, and sonicating for 24 hours, where the ultrasound process water temperature must not be higher than 70 degrees C, then centrifuging obtained polypeptide/graphene mixture for 10-30 min at a centrifugation speed of 500-8000 revolutions/minute, and separating the supernatant to obtain graphene dispersion.